Mars Sample Return quarantine & recovery (1985)

Beginning in late 1983, a team of engineers and scientists from NASA's Johnson Space Center (JSC), the Jet Propulsion Laboratory, and Science Applications Incorporated jointly defined a Mars Sample Return (MSR) spacecraft and mission plan (top link below). Among their proposed follow-on study objectives for Fiscal Year 1985 was to better define Mars sample quarantine protocols and associated risks. In addition, the team recognized the need to rapidly recover the Mars sample after its arrival at Earth.

JSC's Solar System Exploration Division contracted with Houston-based Eagle Engineering to examine these issues and provide "rough" cost estimates. In its study, performed between May and September 1985, Eagle explored 10 options for retrieving a Mars sample following its return to Earth.

Eagle found that Direct Entry into Earth's atmosphere, with an estimated price tag of from $5.2 million to $9.8 million, would be the simplest and cheapest Mars sample recovery option, but would also carry the greatest risk (one chance in 600,000) of contaminating the terrestrial environment with potentially "malignant" martian microbes. Eagle acknowledged, however, that its contamination risk estimates (which, it explained, were based on "limited data") were arbitrary.

In Direct Entry, a reentry capsule carrying the sealed Mars sample canister would intersect Earth's atmosphere over the Pacific Ocean near Hawaii traveling at upwards of 11 kilometers per second. An ablative coating would protect the capsule from reentry heating. Eagle noted that a shallow atmosphere-entry angle would subject the sample canister to a long heat pulse, a low deceleration load, and imprecise landing site targeting (and, therefore, possible delayed recovery), while a steep angle would yield a short heat pulse, a high deceleration load, and more precise targeting.

After slowing to subsonic speed, the capsule would deploy a 5.5-meter-diameter parachute. A Defense Department transport aircraft - probably a C-130 - would snatch the descending capsule by the parachute in midair and winch it into its cargo hold, then would fly directly to the Centers for Disease Control (CDC) in Atlanta, Georgia, or to a newly constructed Planetary Sample Receiving Laboratory (PSRL) in a remote location. Eagle did not include the $14-million cost of the new lab in its cost estimates. The company assumed that the C-130 would be one of three similarly configured air-snatch planes in the recovery area, each of which would carry 11 aircrew on board.

Eagle's second option was Shuttle Recovery, which, the company estimated, would have only one chance in 100 million of releasing potentially harmful martian microbes into the terrestrial environment. A delta-winged Space Shuttle Orbiter would be prepositioned in Earth orbit in anticipation of the arrival of an Earth Return Vehicle (ERV) bearing the sample canister. The ERV would skim through Earth's upper atmosphere to use drag to slow down (that is, it would aerobrake) and enter an elliptical Earth orbit. It would then discard its protective aeroshell and fire a rocket motor at the apoapsis (high point) of its orbit to raise the periapsis (low point) of its orbit above the atmosphere and circularize its path around the Earth.

Eagle noted that the Shuttle Orbiter was incapable of climbing higher than about 500 kilometers above the Earth (in fact, it reached about 610 kilometers during STS-31, the Hubble Space Telescope deployment mission, in April 1990). If the ERV's orbit following the apoapsis burn was above the Shuttle altitude limit, then the Orbiter would need to deploy a teleoperated Orbital Maneuvering Vehicle (OMV). The OMV would match orbits with the ERV, dock with it, lower its orbit, and then separate.

After the Shuttle Orbiter rendezvoused with the ERV, the astronauts would capture it using their spacecraft's robot arm and place it inside a seven-ton biological containment/sample cooling container in the Orbiter's payload bay for return to Earth. The container would, Eagle wrote, be designed to survive intact a Shuttle accident during reentry and landing. A slightly cheaper but "significantly" more risk-fraught alternative would be for a spacewalking astronaut to extract the sample canister from the ERV and carry it into the two-deck Orbiter crew cabin for return to Earth.

Eagle placed the cost of the Shuttle return option at between $150 million and $173 million, of which $120 million would, in theory, pay for the Space Shuttle flight (in practice, Space Shuttle flights were considerable more expensive than this). The company also examined recovery of the sample from a high elliptical Earth orbit (the 1984 JSC/JPL/SAI design study proposed that the ERV capture into such an orbit). Eagle found that the Orbital Transfer Vehicle (OTV) required to reach such an orbit would boost their estimated cost by from $50 million to $100 million.

Eagle's third recovery option was Recovery to Space Station Structure. The company estimated that for this and all subsequent recovery options, the likelihood that harmful martian microbes could escape into Earth's environment would be less than one chance in 100 million. A Shuttle Orbiter would deliver to NASA's Space Station in 500-kilometer-high Earth orbit a biological containment/sample cooling container and three tons of propellants for a Station-based OMV. This would, the company noted, make use of about half the Shuttle's payload capacity, leaving the other half for additional Station-bound cargo unrelated to the sample recovery operation.

Spacewalking astronauts would attach the containment/cooling container to the Station's exterior. Some time after that, the ERV would aerobrake and maneuver into a circular orbit. The Station crew would then dispatch an OMV to recover it and bring it to the Station.

The Station's robot arm would transfer the ERV from the OMV to the containment/cooling container. A Shuttle mission to the Station would then collect the container for return to Earth, along with about half a payload bay of Earth-bound cargo unrelated to the sample recovery operation. Eagle placed the cost of this option at between $167 million and $193 million.

Option 4, Space Station Sample Repackaging, would see a Shuttle Orbiter deliver parts for modifying the Life Sciences Module (LSM) airlock that was expected to be part of the Space Station along with propellants for a Station-based OMV. Alternately, a Shuttle mission would detach the LSM from the Station and transport it to Earth for modification, after which a second Shuttle mission would return it to the Station.

The OMV would capture the ERV and deliver it to the LSM airlock, where astronauts would extract the sample canister and repackage it within a small biological containment/sample cooling container. The container would then be returned to Earth inside a Shuttle Orbiter crew cabin. The ERV would remain in quarantine inside the LSM airlock until scientists in the PRSL on Earth had analyzed the returned Mars sample and determined that it posed no threat. Eagle estimated that this option would cost between $302 million and $714 million.

Option 5, for which Eagle had little enthusiasm, was dubbed Minimal Sample Analysis at Space Station. It would closely resemble Option 4, except that a small sub-sample would removed from the sample canister in the LSM for "minimal" biological analysis. "There is some question," the company noted, "as to how much use a minimal analysis would be." Eagle placed the cost of this option at between $316 million and $749 million.

Eagle's Option 6, Small Sample Sterilized at Station and Sent to Earth, was also derived from its Option 4. Astronauts would remove a sub-sample and heat it enough to kill martian microbes while preserving evidence of their existence. A Shuttle Orbiter would then transport the sub-sample to Earth. The remainder of the sample (and, possibly, the Station crew) would remain in quarantine until scientists in the PSRL had checked out the sub-sample. Eagle placed this option's cost at between $316 million and $927 million.

After Option 6, Eagle's proposed sample-handling options became much more complex and expensive, adding significantly to the cost of returning a sample from Mars. Option 7, Separate Quarantine Module Attached to Station, would see a Shuttle Orbiter dock a specialized LSM-derived Quarantine Module (QM) to the Station. Eagle noted that the cost of "[d]edicated facilities. . .will seem more reasonable if a number of sample return missions are envisioned," and added that "[m]anned Mars missions might. . .use the [QM]" for quarantine of astronauts returning from Mars.

No pressurized passageway would link the Station to the QM while it held a Mars sample. If the QM was a permanent module of the Space Station, then it might be connected to it by a pressurized tunnel when no Mars sample was present and put to non-sample-related uses.

Alternately, the QM might be attached to the Station only when a sample was due to arrive from Mars. After the sample was placed in the QM, a Shuttle Orbiter would detach the module and transport it to Earth. Another Orbiter would return the empty QM to the Station when the next Mars sample was due to arrive in Earth orbit. Eagle estimated that Option 7 would cost between $605 million and $1.04 billion.

Antaeus Lab Module Attached to Station, Eagle's Option 8, took its name from the 1981 Antaeus report (bottom link below), which described a purpose-built Orbital Quarantine Facility (OQF) space station. The Antaeus module, which would be capable of supporting long-term detailed sample analysis on much the same scale as the Earth-based PRSL, would replace or augment the Station's LSM.

If researchers working in the Antaeus module found that the Mars sample was safe, then it would be transported to Earth. If, on the other hand, the sample were found to contain harmful martian microbes, then the Antaeus module would be detached and boosted into a 1270-kilometer-high long-term orbit using an OMV. In the event that harmful microbes escaped from the Antaeus module and contaminated the Space Station, then an OMV could boost the entire Station into a 650-kilometer-high orbit. Eagle estimated that orbit-raising maneuvers could extend the orbital lifetime of the Antaeus module or Station for long enough to permit NASA to develop a large rocket stage that could boost the contaminated Antaeus module or Station into interplanetary space.

Augmenting the Space Station with the Antaeus module would require perhaps eight Shuttle flights at an estimated cost of $120 million each, for a total of $960 million. The company placed the total cost of Option 8 at between $1.863 billion and $2.456 billion.

Eagle's Option 9, the 1/2 Quarantined Space Station, would be nearly identical to its Option 8, except that the Station modules that would support the scientists analyzing the sample in the Antaeus module would be isolated from the rest of the Station. This would be achieved by closing pressure hatches between the two halves of the Station and slightly reducing air pressure in the quarantined modules. Eagle expected that this option would cost the same as Option 8, though it added that "detailed study may show this option to have a somewhat higher cost."

Option 10, a Dedicated Antaeus Space Station identical to that described in the Antaeus report, would constitute a new (albeit small) independent space station in Earth orbit, making it the costliest of the 10 options. Eagle estimated that the Antaeus station would cost between $5.101 billion and $7.107 billion. This option would make unnecessary the PSRL on Earth since all quarantine and analysis would take place in Earth orbit. The company declared that Option 10 was "without a doubt the safest, biologically, of all the options," but added that "the price paid for this additional safety seems unreasonably high."

Having examined the 10 options, each more complex than the last, Eagle judged that Options 1, 2, and 3 would be adequate for Mars sample quarantine. The probability of a biological accident involving a Mars sample was simply too minute to justify the greater cost of Options 4 through 10.

The company then examined methods of Earth-orbital sample recovery. It assumed that, during Mars-Earth transfer, the sample would be preserved at cold Mars-like temperatures to maintain its scientific integrity. Earth orbit is, however, warmer than interplanetary space because Earth radiates heat. This would make difficult keeping the Mars sample cold for long periods in Earth orbit, so rapid recovery would be desirable.

Eagle also assumed that an ERV that employed rocket motors to slow itself so that Earth's gravity could capture it would end up in a high elliptical Earth orbit (700 kilometers by 40,000 kilometers or 700 kilometers by 70,000 kilometers, with orbital periods of 12 or 24 hours, respectively). This would have the advantage of placing it well away from the Earth's radiated heat through most of its orbit, but would also delay sample recovery.

For recovery from elliptical orbit, the planned OMV design would be inadequate, so Eagle invoked a new-design Orbital Transfer Vehicle (OTV) based on the Centaur upper stage. Recovery using an OTV based at the Station would be problematic because the Station's orbital plane would shift 6° per day relative to the ERV, forcing the OTV to burn a considerable quantity of propellant to match orbits with the ERV and return with it to the Station. Eagle found that the best-case recovery time for a sample in elliptical orbit would be equal to one orbital period (12 or 24 hours) plus about four hours, leading to totals of 16 or 28 hours.

A sample in a 500-kilometer circular orbit, on the other hand, would be subjected to more Earth-radiated heat, but could be recovered by a Shuttle Orbiter or an Orbiter- or Station-based OMV in as little as six hours. Providing the ERV with enough propellant to circularize its orbit at 500-kilometer altitude would, however, increase its mass by 2.5 times over the elliptical-orbit ERV. This would constitute "an unacceptable penalty," Eagle judged.

Planetary Sample Rapid Recovery and Handling, Report No. 85-105, Eagle Engineering, September 20, 1985.

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Cislunar cycler (1991)

The Space Exploration Initiative (SEI), launched on the 20th anniversary of the Apollo 11 lunar landing (July 20, 1989), differed from most other presidential space initiatives in that President George H. W. Bush and members of his Administration apparently truly believed in it. Bush, the 41st President of the United States, had been in office for only six months at the time he made his announcement on the steps of the National Air and Space Museum, so he did not perceive SEI mainly as a component in his re-election campaign. This was unlike President Richard M. Nixon, who delayed announcement of the Space Shuttle Program until January of the 1972 election year, President Ronald W. Reagan, who announced the Space Station in January of the 1984 election year, and President George H. W. Bush, who announced the Vision for Space Exploration in January of the 2004 election year.



Though among SEI's many failings was a flawed execution, Bush 41 did his best to support his initiative after he had announced it. Again, this differed from Nixon, Reagan, and Bush 43. Because of its rumored cost of a trillion dollars, SEI became a political liability for Bush; nevertheless, as late as the summer of 1991, he gave speeches about it and negotiated with Congress for funds to keep it alive in some form.



Bush was not reelected in 1992, and SEI ended soon after President William J. Clinton took office in January 1993. Bush's initiative was not, however, without result. It left behind it a substantial legacy in the form of a vast body of literature, a motherlode of ideas for ways to explore the moon, Mars, and, to a lesser extent, other destinations. Not since the 1960s space race had American aerospace engineers had the opportunity to be so creative.



In February 1991, for example, Chauncey Uphoff and Robert Crouch, engineers at Ball Space Systems Division in Boulder, Colorado, described a cycler system for regularly scheduled voyages between the Earth and its peculiarly oversized natural satellite. Cycling spacecraft take advantage of planetary gravity-assist flybys to continuously repeat voyages between at least two worlds with minimal use of rocket propellants. Almost all cycler designs proposed to date have been intended to link Earth and Mars.



Their cislunar cycler system would include at least two spacecraft, the design of which Uphoff and Crouch did not specify. It is logical to assume, however, that they would be derived from space stations meant to operate beyond the safety of low-Earth orbit (LEO). The images above show two such station designs. The middle image shows a 2002 NASA concept of an Earth-moon L1 "Gateway" station with many inflatable components, while the bottom image illustrates a North American Rockwell lunar-orbit station concept from the early 1970s.



The cyclers would carry the most massive equipment and structures needed for economical and safe cislunar transport - for example, a recycling closed-loop life support system and ample radiation shielding for protecting the passengers from solar flares and cosmic rays - plus a propellant farm for refueling small "taxi" spacecraft that would carry passengers and cargo to and from the cycler. The cycler would be launched from LEO only once, yet could complete many Earth-moon journeys. In effect, it would be a permanent space station following a complex path through the Earth-moon system. Compared with, say, an Apollo-type Earth-moon transportation system, the cycler system's propellant requirements would be negligible.



The twin cyclers would follow three kinds of paths through cislunar space. Used in combination, they would enable a lunar swingby every 14 days, with each cycler encountering the moon three times in two months.



The first of the three cislunar paths, an elliptical Earth-moon "transfer orbit," would need either nine days or 14 days to complete. The second, a novel circular high-inclination "BackFlip" moon-to-moon transfer, would need 14 days. The third, a circular "holding orbit" that would match the moon's orbit but be inclined slightly relative to its orbital plane, would need 28 days to complete.



Low-thrust electric (ion) thrusters would perform almost all routine cycler course adjustments once the pattern of Earth-moon transfers became established. These would have the advantage of requiring minimal propellant, thereby reducing the logistics burden of operating the cycler system. In short, electric propulsion would reduce the number of costly launches from Earth's surface that would be needed to keep the cislunar cycler system running.



The twin cyclers would also carry high-thrust rocket motors for emergency maneuvers. These would burn chemical propellants drawn from the taxi propellant farm.



Uphoff and Crouch described their cislunar cycler system in action by following the movements of one cycler spacecraft. At the beginning of its career, a chemical-propellant booster would launch the cycler from its LEO assembly orbit toward the moon on a trip that would last from 4.5 to seven days. As it flew past the moon, its passengers would enter taxis and undock to land at the moon base or capture into lunar orbit.



The cycler, with no one on board, would then perform a gravity-assist lunar swingby that would take it into a BackFlip inclined 46° relative to the plane of the moon's orbit about the Earth. The spacecraft would remain within 318,000 kilometers of the moon (78% of the Earth-moon distance of 397,000 kilometers) during the BackFlip. Because of this, it would undergo gravitational perturbations to its orbit that it would need to correct using its electric thrusters.



Fourteen days after beginning the BackFlip, the cislunar cycler would for the second time encounter the moon, this time on the opposite side of the moon's orbit from the place where the first swingby took place. By applying electric-propulsion thrust selectively during the BackFlip, the cycler would reach the moon for the second time already positioned to enter either a 14-day or nine-day Earth-moon transfer orbit or a 28-day holding orbit.



If the cycler aimed for Earth, then passengers bound for the homeworld would leave the moon in taxis and dock with it during the second lunar swingby. Uphoff and Crouch suggested that the cycler carry chemical-propellant tugs for rescuing taxis that suffered propulsion or docking failures. The voyage to Earth would require 4.5 days (for a nine-day transfer orbit) or seven days (for a 14-day orbit). As the cycler neared Earth, the taxis would undock and aerobrake in the atmosphere to shed speed and capture into LEO, where they would rendezvous with the space station.



The unmanned cycler, meanwhile, would swing by Earth and complete the second half of its nine-day or 14-day orbit, in theory reaching apogee (its farthest point from Earth) at lunar distance (in practice, some nine-day orbits would not reach apogee at lunar distance, Uphoff and Crouch noted). The moon would not be there when the cycler attained apogee: instead, it would be located either one-third (for a nine-day orbit) or halfway (for a 14-day orbit) around its 28-day orbit from the point where the cycler reached apogee.



The cycler would then return to Earth in 4.5 days or seven days. If in a 14-day orbit, passengers bound for the moon would fly taxis to the cycler during this second Earth swingby. The cycler would then re-encounter the moon seven days later and drop them off. If in the nine-day orbit, the cycler would swing past the Earth unmanned and again reach apogee without the moon nearby 4.5 days later. It would then fall back to Earth. During its third Earth encounter, it would collect passengers, which it would deliver to the moon 4.5 days later.



If no one had need of a ride to Earth when the first BackFlip brought the cycler back to the moon, the unmanned cycler would enter a 28-day holding orbit. The holding orbit was, Uphoff and Crouch explained, an unfortunate necessity, for orbital mechanics dictated that BackFlips not occur in succession. This was because the lunar swingby needed to begin a new BackFlip immediately after completing one would occur below the lunar surface. In other words, the attempt would crash the cislunar cycler into the moon.



At the end of its 28-day holding orbit, the cycler would re-encounter the moon and, if passengers needed to travel from the moon to the Earth, would commence another nine or 14-day Earth-moon transfer orbit. Alternately, the unmanned cycler would begin another BackFlip, swinging by the moon again 14 days later.



Once every six weeks, the twin cyclers would fly past the moon at the same time. They could then enter a nine-day or a 14-day Earth-moon transfer orbit together, allowing them to dock for 28 days before they encountered the moon again. During this period, astronauts would board the cyclers to perform repairs and maintenance and restock supplies.



To reestablish the cislunar cycler system's pattern of one lunar encounter every 14 days, the cyclers would undock when next they encountered the moon. One would then enter a 14-day BackFlip, while the other would enter a 28-day holding orbit.

"Lunar Cycler Orbits with Alternating Semi-Monthly Transfer Windows," C. Uphoff and M. A. Crouch, AAS 91-105, Spaceflight Mechanics 1991, pp. 163-176; paper presented at the AAS/AIAA Spaceflight Mechanics Meeting held in Houston, Texas, February 11-13, 1991.

Using Columbia to begin bringing the moon to America (1996)

Assembly of NASA's first spaceworthy Space Shuttle orbiter, OV-102 Columbia (middle image above), commenced in November 1975. The 111-ton reusable winged spaceship first reached low-Earth orbit on STS-1 (April 12-14, 1981), the Space Shuttle Program's first mission. Named for the first American sailing ship to circle the globe and the Apollo 11 Command and Service Module, Columbia completed 27 successful flights.

NASA's oldest Orbiter was also its heaviest. Unlike its sisters Atlantis, Discovery, and Endeavor, Columbia could not reach the 51.6° orbital inclination of the Russian Mir station and the International Space Station (ISS) with a useful payload in its 15-by-60-foot payload bay. This performance constraint meant that, in the Shuttle-Mir/ISS era, NASA increasingly relegated to Columbia its few remaining low-inclination, non-space station missions, such as Hubble Space Telescope servicing. Extended-Duration Orbiter modifications also permitted Columbia to remain in orbit for more than two weeks to serve as a science research platform, but such missions would become increasingly rare after research commenced on board ISS.

In an April 1996 paper presented at the 33rd Space Congress in Cocoa Beach, Florida, Carey McCleskey of the Vehicle Engineering Directorate at NASA's Kennedy Space Center proposed using the oldest Orbiter's excess mission capacity "to ignite a billion dollar, sustained enterprise on the Moon." Specifically, he advocated using Columbia as a joint NASA/private sector Earth-orbital launch platform for rocket stages bearing small lunar landers. Columbia would remain in space for only a few hours during each of its lunar lander deployment missions.

The landers would deliver to the moon teleoperated "micro-robots" akin to Mars Pathfinder's Sojourner rover (bottom image above). These would serve as proxy lunar explorers for paying visitors at "space theme parks" on Earth.

Confident that his proposal would help to build public support for U.S. astronauts to return to the moon, McCleskey wrote that

use of Columbia only makes sense for the start-up and initial take-off phases of the enterprise. The Shuttle system. . .will reach a limit which will drive the nation toward advanced space delivery systems. The use of the Shuttle for starting a lunar enterprise, therefore, is not the answer for space delivery, but rather our next opportunity.

Columbia lifted off at the start of STS-107, its 28th mission, on January 16, 2003. Eighty-two seconds after launch, a piece of foam insulation about 20 inches long broke free from its External Tank and struck its left wing. Engineers examining high-resolution video images of the impact warned of possible wing damage, but Shuttle management elected to disregard their warnings.

The oldest Orbiter's seven-person crew conducted wide-ranging science research for 16 days - long enough for the moon to wax from nearly full to full, then wane to last quarter and new. The crew beamed to Earth a breathtaking image of the last quarter moon taken on January 26 (top image above).

On February 1, 2003, the day of the new moon, Columbia fired its twin Orbital Maneuvering System engines to slow itself and reenter Earth's atmosphere. Temperatures on the Orbiter's belly tiles, nose cap, and wing leading edge panels began to climb as Columbia reentered at an altitude of 400,000 feet. About 40 minutes after the deorbit burn the wing leading edge temperature neared its peak value of about 3000° Fahrenheit.

As Columbia crossed the California coast in predawn darkness en route to its planned landing in Florida, hot plasma began to penetrate its internal structure through a breach in its left wing leading edge. Flight controllers in Mission Control in Houston puzzled over the cause of sensor failures in the Orbiter's left wing. The failures progressed aftward from the leading edge.

For observers on the ground in California, Nevada, Utah, Arizona, Colorado, New Mexico, and Texas, many of whom had observed pre-dawn Shuttle reentries before, Columbia was a fast-moving, brilliant point of light leaving behind a luminous, sky-spanning ionization trail. Veteran observers along Columbia's reentry path noted more than 20 unusual flashes around the Orbiter and peculiar bright streaks in the trail.

As Columbia crossed from New Mexico into Texas, it began to shed pieces. Meanwhile, thrusters fired automatically to compensate for increased drag on the left wing. Columbia did not give up without a fight.

Radio contact with Columbia was lost about 10 minutes after hot plasma first entered the left wing. Less than a minute later, the gutted wing folded over the fuselage. The oldest Orbiter disintegrated at an altitude of 203,000 feet just west of Dallas, Texas, killing its crew and raining wreckage over parts of eastern Texas and western Louisiana.

The STS-107 accident triggered far-reaching changes in the U.S. space program that have yet to play out fully. The most obvious of these was President George W. Bush's January 2004 call to end the Space Shuttle Program when ISS was completed, which at the time was scheduled for 2010. The 135th and last flight of the Shuttle, designated STS-135, concluded on July 21, 2011, with the landing of Atlantis in Florida. On August 16, 2011, Space Shuttle Program Manager John Shannon announced that the Shuttle Program would end officially on August 31, 2011.

"Using the Space Shuttle Columbia to Begin Bringing the Moon to America," Carey M. McCleskey; paper presented at the 33rd Space Congress in Cocoa Beach, Florida, April 23-26, 1996.

The Cow jumped over the moon (1957)

In June 1957, launch of the U.S. Vanguard 1 satellite (bottom image above) was thought imminent. That month, Krafft Ehricke and George Gamow wrote in Scientific American magazine that, after the artificial satellite reached orbit, "the next interesting target in space" was the moon. They estimated that, with "luck and sufficient effort," an automated probe could reach the moon by 1963.

Ehricke and Gamow proposed a design for such a probe, which they dubbed "Cow" in tribute to the moon-jumping nursery rhyme character. Cow would have a mass of between 400 and 800 pounds. A 100-foot-tall, 120-ton rocket would boost it to a speed of 23,827 miles per hour on a path toward the moon. If the Earth existed in isolation, Cow would then enter an elliptical orbit around the Earth taking it 280,000 miles out into space - that is, about 40,000 miles beyond the moon. The gravitational attraction of the moon and Sun meant, however, that Cow would follow a "distorted" path to a point 1281 miles from the moon 75.6 hours after launch. The probe would then swing around the moon, collecting data all the while, and fall back to Earth.

Cow would strike Earth's atmosphere moving at 25,000 miles per hour 157 hours after launch. Though high-speed reentry would drive Cow's skin temperature to 5000° Centigrade, Ehricke and Gamow maintained that "preventing the capsule from burning up by means of insulation and a cooling system" would not be "technically prohibitive." This would enable recovery of photographic film and recorded data.

Ehricke and Gamow then proposed a follow-on lunar sample-collection mission that would employ two probes launched on a "Cow-type" trajectory. The lead probe would drop an atomic bomb on the moon, blasting a debris cloud far into space; then, through "a miracle of electronic guidance," the trailing probe would "dive into the cloud, collect some of the spray and emerge from its dive by means of an auxiliary jet." It would then fall to Earth for recovery.



On October 4, 1957, the Soviet Union launched the first Earth satellite. Vanguard exploded on its launch pad on December 6, 1957, so the U.S. Army's Explorer 1 became the first U.S. Earth satellite (January 31, 1958). Soon after, both the U.S. and U.S.S.R. began to launch probes toward the moon (see link below). The Soviet Luna 2 spacecraft became the first human-made object to strike the moon on September 13, 1959, and Luna 3 imaged the moon's hidden Farside on October 6, 1959. No spacecraft would fly Ehricke and Gamow's Cow-type trajectory until the Soviet Zond 5 (an unmanned test of a manned circumlunar spacecraft) in September 1967, and none would return samples of lunar surface material until the first manned moon landing (Apollo 11, July 16-24, 1969).

A Rocket Around the Moon, K. Ehricke and G. Gamow, Scientific American, Volume 196, Number 6, June 1957, pp. 47-53.



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